Serum iron in catatonia and neuroleptic malignant syndrome

Preliminary data suggest that decreased serum iron levels predict the progression of catatonia to neuroleptic malignant syndrome (NMS). This study examines the predictive value of low serum iron in this NMS conversion and explores other potential significance of serum iron in catatonia.

Fifty patients with catatonia were prospectively identified at two psychiatric intensive care units during a 3-year period [incidence of 5% (39/716) and 13% (11/86) respectively]. Serum iron was measured in 39 episodes. Seventeen episodes (44%) showed low serum iron levels. A retrospective chart review of patients identified was conducted, comparing those with low and normal serum iron levels.

Low serum iron levels were associated with malignant catatonia, excited catatonia, and poor responses to benzodiazepines. There were 7 episodes of malignant catatonia. All had low serum iron. Neuroleptic were used in 5 of them, and all 5 evolved into NMS. No such NMS conversion was noted in those with normal serum iron or in nonmalignant catatonia with low serum iron. Seven episodes (with low serum iron) failing benzodiazepine therapy responded subsequently to lithium-neuroleptic combination therapy.

Malignant catatonia, associated with low serum iron, is at high risk of evolving into NMS. Low serum iron in nonmalignant catatonia does not predict this NMS conversion. Excited catatonia as a catatonic subtype (associated with low serum iron and unfavorable benzodiazepine responses) deserves more research attention. There appears to be a possible connection between treatment resistance to benzodiazepines, favorable responses to lithium-neuroleptic combination, and low serum iron.